Want to build something like those super slick web applications coming out of Google, like Gmail, or Google Maps? Part of the trick is using the XMLHttpRequest object and Javascript for request new data behind the scenes. I’ve used this technique to solve a problem on a large-scale traveling site here in Denmark. While you need to do some SOAP goo to get it working, it does work like a charm.

One of the classic drawbacks to building a web application interface is that once a page has been downloaded to the client, the connection to the server is severed. Any attempt at a dynamic interface involves a full roundtrip of the whole page back to the server for a rebuild--a process which tends to make your web app feel inelegant and unresponsive. In this article, I'll be exploring how this problem can be tackled with the use of JavaScript and the XMLHttpRequest object.